how to assign html value into hidden field

Question

 My code as follows

 

<div class="dropDownParent1" style="float: left; width: 250px; height: 25px;">

  <select id="ms" multiple="multiple" style="float: left; width: 250px;" class="ms" title="Select                 Project">

</select> 

</div>

 

 

how to assign the above id="ms" into hidden field.

 

please help me.